XD Talk

bigmoguls · 07-21-2012, 06:26 PM

I have an '07 Lincoln MKX. Got in it today after it was sitting in the hot sun for two hours (97 degrees). The AC would only blow cool while the car was moving. After about 25 minutes, it appeared to start blowing cold while stationary. Anyone have any suggestions?

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AwPhuch · 07-21-2012, 06:32 PM

Check the freon level...could be a tad bit low (R-134a is a much smaller molecule than R-22 thus is seeps out easier if there are old worn seals)

Also...at idle on a very hot day...might not be pulling enough air thru the condenser to adequately cool the freon and create the volume liquid to flow thru the expansion valve to cool enough (this also could mean it isn't compressing enough freon either...optimum compressor RPM's are around 2K)

Also check the fans/clutch assembly (if its a forward facing engine)/electric motors...if they are not coming on its not pulling air thru the condenser/radiator

Does your AC blow cold if you bump up the RPM's on the engine to around 2K (normal cruise speed on OD at 65mph) or not? Does it blow colder when you are cruising down the freeway vs sitting still?

97 degrees on the outside sitting in the sun = 140 on the inside, a closed vehicle sitting in the sun turns into an OVEN, always good to park in the shade or slightly crack the windows to allow the hot air to at least have someplace to go, or roll all your windows down for 5 minutes and let the latent convective heat escape before you try to cool 140 degree air to 60 degrees.

P.S. Welcome to Texas...where during the summer time, its no longer the closeness to the doors but the proximity of shade is the determining factor on where you park in the parking lot

P.S.S. Dark vinyl or pleather in the sun will practically bond with human skin if you wear shorts...I found out the hard way

Andy_PHA · 07-21-2012, 06:40 PM

My guess would be the compressor clutch is going bad. At the lower RPM's it is slipping and not compressing the freon, then once the RPM's get higher the clutch catches and starts working normally. Also I've never sat in a car that had ice cold air immediately when getting in it after a long day in the sun. The air is so hot to begin with that it takes a bit for the energy exchange to take place and start cooling down the air. But my assumption here is that you are noticing a difference from how it typically performs.

bigmoguls · 07-22-2012, 08:05 PM

I did a little more experimentation today.

1st - this is an operational change for this car, I don't recall it doing this before.

It will blow warm air, while stationary even if the RPMs are 2-2.5k. However, after about 20 minutes of operation, it appears to operate as normal, cold air even while stationary.

I think it has something to do with the temperature of the car, when I start the car, I can hear the compressor engage, the rpms drop a little, and cold air comes out for a brief moment (about 15 seconds), however, once driven, operation returns to normal.

guitarnstuff · 07-22-2012, 08:29 PM

Time for the Jeep effect. Remove top and doors. A sawzall should work just fine or a trade in.

Arney · 07-22-2012, 10:21 PM

Try a recharge. Even one can of freon can make a difference. If it lasts only a few days...than you have a leak, but doubt if thats your issue. Also look into R12A if you have time ...larger molecules and fully compatable with 134 or R12.